A NEW IN SITU STRESS DETERMINATION TECHNIQUE FOR CONCRETE BRIDGES

This paper describes an adaptation of the centre hole/stress-relief method for determining in situ stress in concrete structures. The new method enables smaller hole diameters, typically between 36mm and 52mm, to be used with the same degree of accuracy, but with less damage to structural members, so that it can be used where other techniques are unsuitable. However, it is necessary to allow for the effect of shrinkage stresses, which increases as the hole diameter decreases. Several tests were performed in the laboratory, to provide a reference for the theoretical analysis of the method. A series of finite element models were run, for comparison with experimental results. Good correlation was found between them. These results, and the results of in situ testing, confirmed the accuracy of the method. The sensitivity of the new coring method, with multiple small hole geometry, was found to be comparable to that of the single larger hole used before. It also provides a more detailed description of the stress field within the component, and is less sensitive to localised stress variations. For the covering abstract see IRRD 869077.